U.S. Vice President Joe Biden says China's new air defense identification zone over the East China Sea has caused "significant apprehension" in the region.

Biden said he had transmitted the Obama administration’s firm objections to the zone in his talks in Beijing with Chinese President Xi Jinping on December 4.

China’s Foreign Ministry said officials had told Biden that the zone was in accordance with international law and that the United States should respect it.

The zone covers an area that includes islands whose ownership is contested by China and U.S. ally Japan.

Since the zone was announced November 23, U.S., Japanese, and South Korean military aircraft have flown through the zone without informing Chinese authorities in advance, as required under the new Chinese policy.